Karaoke machines have become very popular for sing-alongs where the purpose is to have the participants follow the lyrics of songs. Technology has been developed to create echo effects for Karaoke machines as well as in public auditoriums. See for example: U.S. Pat. No. 3,681,531 to Burkhard et al.; U.S. Pat. No. 5,442,711 to Toyama; and U.S. Pat. No. 5,444,785 to Izawa et al. However, these devices are used to enhance and magnify the voices of performers such as singers and the like. No confusing feedback of the voices is anticipated nor desired by these devices.
U.S. Pat. No. 4,630,301 to Hohl et al. describes a voice activated echo generator that can be used as a toy and as a speech learning aid for the deaf. However, the application is strictly described for creating echo effects. Similarly, U.S. Pat. No. 5,127,870 to Lin describes a microphone used for generating echoes. None of these patents are intended to have any confusing feedback distortion for entertainment.
Helmets and masks have been proposed for modifying a wearer's voice. See for example, U.S. Pat. No. 4,683,588 to Goldberg and U.S. Pat. No. 4,949,378 to Mammone. However, each of these patents alters the voices by scrambling, camouflaging and disguising the actual voices. U.S. Pat. No. 5,149,104 describes a video game and audio player interaction with real time video synchronization, where player can have their voices modified to reflect video images of objects and animals and the like. For example, the patent mentions an instance where a speaking player has their voice modified to sound like a sheep so that the image of the sheep is emitting animal sounds. None of these patents are intended to have any confusing feedback distortion for entertainment.